This invention relates to an improved double-acting, nonexpansion, noncondensing, piston steam engine.
The first commercially successful steam engine was patented by Thomas Savery in 1698. Savery's engine and its improved versions were used to pump water out of flooded underground mines in all parts of the world until the late eighteenth century. In all of these engines, steam acted either by its momentum alone or by exerting pressure directly on the surface of water.
The important idea of using steam to act against a piston in a cylinder appears to have originated with Denis Papin. About 1690, he constructed a model of a steam engine comprised of a vertical cylinder with a piston. While Papin neglected his own idea to develop Savery's engine, Thomas Newcomen proceeded with development of Papin's idea and patented the first steam engine really worthy of the designation in 1712. Newcomen's engine was a single-acting, condensing, vertical piston steam engine known as an "atmospheric" engine because it used steam at atmospheric pressure.
Beginning in the 1760's James Watt introduced a scientific approach to the development of the steam engine. In 1769, Watt patented an improved Newcomen engine. Watt patented a double-acting steam engine in 1782. In that engine, the steam pushed alternatively on both sides of the piston thereby providing a working force during each stroke and doubling the output of a given size of engine. During this era, Watt and his associates were responsible for other inventions which were directly applicable to the steam engine, including a crank and connecting rod for a steam engine, a sun-and-planet gear, a throttle valve, a governor for regulating speed, a counter for recording the number of piston strokes, and an indicator for ascertaining the work done by steam. These contributions to the development of the steam engine played a large role in ushering in the Industrial Revolution.
The steam engine dominated the Industrial Revolution and made available a practical source of power for both stationary and mobile applications. During its zenith in the late nineteenth century and early twentieth century, the steam engine supplied most of the power needs of the world. With the introduction of the steam turbine as a prime mover for electric generating stations and the internal combustion engine as a prime mover for mobile power applications, the role of the steam engine as a power source was diminished. Accordingly, no serious developmental activities relating to the steam engine have taken place in the twentieth century prior to various changed socio-economic circumstances in the mid-1970's which have renewed interest in the steam engine.
Since the mid-1970's, the cost of energy generated by burning the world's primary fossil fuels, i.e. coal, oil and natural gas, has increased substantially. Furthermore, because of various social and economic considerations, nuclear fuels have not made as significant a contribution toward meeting the world's total energy requirements as was earlier anticipated. And, the technology necessary for solar energy to make a significant contribution toward meeting these requirements has not been available to date. For these and other reasons, the use of alternate fossil fuels to supply a portion of the world's total energy requirements has become substantially more attractive to energy use planners than was earlier the case. Various alternate fossil fuels, such as wood by-products and waste from the lumber, furniture, plywood and pulp industries, vegetable by-products and waste from the various farming and food products industries, animal by-products and waste from the various animal husbandry and food products industries, treated solid waste from municipal waste treatment facilities, and selected portions of the solid material from municipal garbage disposal operations, are suitable for generation of energy. However, since such fuels have a substantially lower energy content than is the case with the primary fossil fuels, it is generally believed that the alternate fossil fuels cannot be economically used if they must be transported to a large energy generating facility. Accordingly, it is desirable to have small but efficient means for burning such fuels and converting the resulting heat energy to mechanical energy at or near the locations where such fuels are available as by-product or waste materials.
Most of the alternate fossil fuels are not suitable for burning in the internal combustion engine. If such fuels are to be used, they must be burned to heat water for generation of steam. The steam can be used to produce mechanical work for turning a conventional electrical generator. It is well known by those skilled in the art that a small steam engine is more efficient for this purpose than a small steam turbine. And, of course, the aforementioned transportation economics for the alternate fossil fuels dictates the use of smaller-sized equipment.
If the steam engine is to be used as a component of a modern power generation system, major improvements are necessary to reduce thermal and mechanical losses, to improve balance and increase the output rotational speed, and to improve operational reliability. These improvements are needed whether the power generation system is designed for use of alternate fossil fuels or primary fossil fuels. In particular, the steam engine must be capable of continued reliable operation at rotational speeds required for driving modern electrical alternators and generators with minimal thermal and mechanical energy losses.